Compounds structurally related to acetanilide such as acetaminophen and phenacetin are well known to be effective analgesics and antipyretics in man and other mammals. However, a significant adverse effect associated with this group of compounds is cytotoxicity, e.g. acetaminophen is known to cause fulminant hepatic necrosis and phenacetin to cause both hepatic and renal damage in mammals. This invention relates to a chemical modification of this group of compounds to reduce the toxicity yet retain desirable and effective analgetic and/or antipyretic activity.
A compound used in the present invention, 4-methylthioacetaminophen, has been previously identified as a metabolite of phenacetin, but has not been reported to have any biological activity (see article by A. Focella et al, 50 Canadian Journal of Chemistry 2025 (1972)).